Bubble-free and pressure-generating electrodes for electrophoretic and electroosmotic devices

ABSTRACT

Bubble-free electrodes, electrochemical cells including bubble-free electrodes, analytical devices, and methods for preparing and using them are provided. The analytical devices each include at least one bubble-free electrode. Analytical devices that include an electrochemical cell and a sample containment device are also provided, wherein the electrochemical cell includes an anodic reservoir, a cathodic reservoir, an electrical connection between the anodic reservoir and the cathodic reservoir, and a first bubble-free electrode disposed within one of the anodic reservoir and the cathodic reservoir. A second electrode is disposed within the other reservoir and a power source is provided having a positive terminal that is normally in electrical contact with the first electrode, and a negative terminal that is normally in electrical contact with the second electrode. The analytical device further includes a power source polarity-inverting device for switching the contacts between the terminals of the power source and the first and second electrodes. The sample containment device includes a sample containment chamber having an opening for introducing a sample into the chamber and being positioned with respect to the electrochemical cell such that an electrical field generated by the electrochemical cell can influence a property of a component of a sample disposed in the sample containment chamber. Pressure-generating cells are also provided.

BACKGROUND OF THE INVENTION

For many applications regarding the generation of an electric field inan aqueous medium, electrodes are typically placed directly in anaqueous buffer solution and connected to an external power source toform an applied voltage difference. If the applied voltage exceeds aboutone volt, as is typical in electrophoretic and electroosmoticapplications, the applied voltage causes electrolysis of water. Theelectrolysis results in the generation of hydrogen gas at the cathode(negative electrode) and oxygen gas at the anode (positive electrode).

Problems exist in operating microchannel devices and other integrateddevices for sequencing or concentrating biomolecules because of the needfor a connection to an external source of current, usually ahigh-voltage power supply. Conventionally, such connections are made bydipping a wire, such as a platinum wire, in small containers filled withan electrolyte buffer solution. Generated hydrogen gas bubbles andoxygen gas bubbles resulting from electrolysis are vented or escape tothe atmosphere.

In many devices that include an electrochemical cell, the formation ofbubbles at one or both electrode surfaces can create serious problems.These devices include microbiological analytical devices,microelectrophoretic devices, bulk flow transport systems, and deviceswhere electrodes must be placed in confined or sealed fluidic channels.Interfacing of such devices with the electrodes creates particularproblems. Among these problems are siphoning, evaporation ofelectrolyte, excessive current path lengths and associated heatingrequirements, excessively complex electromechanical systems andconfigurations, excessively large systems and electrolyte reservoirs,excessive reagent and/or electrolyte consumption, and in some cases theimpossibility of placing electrodes driven by DC or low frequency ACcurrent inside channels or closed chambers.

Palladium has been used as an electrode material in electrophoreticdevices, for example, the electrophoretic devices described in U.S. Pat.No. 5,833,826, which is incorporated herein in its entirety byreference. In addition, it is well known that palladium absorbshydrogen. However, palladium does not absorb oxygen gas generated at thepositive electrode of an electrochemical cell rendering it undesirableas an electrode material in microbiological analytical devices,microelectrophoretic devices, bulk flow transport systems, and deviceswhere electrodes must be placed in confined or sealed fluidic channels.

SUMMARY OF THE INVENTION

The present invention overcomes problems associated with electrodes thatproduce bubbles by providing a bubble-free electrode material andsystems and methods employing its use. The devices of the presentinvention include one or more bubble-free electrodes, methods ofpreparing bubble-free electrodes, and analytical methods that employdevices including bubble-free electrodes. Herein, the phrase“bubble-free electrode” encompasses different electrodes that produce nobubbles during operation as defined herein.

According to an embodiment of the present invention, bubble-freepalladium electrodes prepared according to the invention are providedthat produce less bubbles than similarly dimensioned palladiumelectrodes not prepared according to the invention under similarenvironmental and electrical conditions.

According to an embodiment of the present invention, bubble-freepalladium electrodes prepared according to the invention are providedthat produce less bubbles than similarly dimensioned platinum electrodesnot prepared according to the invention under similar environmental andelectrical conditions.

According to yet another embodiment of the present invention,bubble-free anodes are provided that do not generate an oxygen bubblevisible to the naked eye when charged at a current density of about 72A/m² (amperes per square meter) for about 1.0 second in a degassedelectrolytic solution under conditions of ready-nucleation, that is,under conditions where spontaneous bubble formation preventssupersaturation of dissolved oxygen.

According to yet another embodiment of the present invention, apalladium anode is provided that includes hydrogen stored in the anodematerial in an amount sufficient to reduce the formation of oxygen gasbubbles by the anode under electrolytic conditions when compared to acomparably dimensioned palladium electrode not including the storedhydrogen.

According to an embodiment of the present invention, an electrochemicalcell is provided that includes one or more palladium anodes that hasbeen pre-charged as a cathode to absorb and store hydrogen within theelectrode structure. Subsequently the electrode is used as an anodeunder electrolytic conditions to operate bubble-free. In an exemplaryembodiment of the present, an electrochemical cell is provided thatincludes a palladium-containing electrode that operates as an anodeunder normal operation of the cell, but that has been pre-charged underconditions as a cathode. During pre-charging, hydrogen generated at thecathode is absorbed and stored in the structure of the cathode. When theelectrode is charged under reverse-electrical polarity conditions, thepalladium metal material absorbs and accumulates hydrogen. After anamount of time has elapsed under the respective reversed electricalconditions, a sufficient amount of hydrogen is absorbed to enable theelectrode to operate under normal operation as a bubble-free anode. Theelectrode can be pre-charged for a predetermined time under therespective electrical conditions such that under subsequent normaloperating conditions, the electrode operates as a bubble-free anode.

The present invention also provides electrochemical cells that includeother hydrogen-absorbing materials as cell electrode materials,particularly as materials for electrodes that normally operate as anodesunder normal operation of the cell. To accomplish storage of hydrogen inpalladium and other hydrogen-absorbing materials, an electrode of thematerial can be run under cathodic conditions prior to being used as ananode. An electrochemical cell including a switch is provided accordingto an embodiment of the present invention whereby the polarity of theelectrochemical cell can be reversed to enable the cell to run underreverse or pre-charging operation.

Whether a switch is provided or the cell is otherwise temporarily causedto operate under pre-charging conditions of reverse polarity,pre-charging can be accomplished to an extent or for an amount of timesufficient to enable the electrode to then operate under anodicconditions as a bubble-free electrode.

According to an embodiment of the present invention, a device foraffecting one or more properties of a component in a sample is providedthat includes a bubble-free electrode. The device can include apalladium electrode as the bubble-free electrode, or some otherelectrode material or combination of materials.

Methods of generating an electrical field with one or more of the anodesand bubble-free electrodes of the present invention are also provided asare methods of separating components in a sample by exposing thecomponents to a field generated by one or more anodes or bubble-freeelectrodes of the present invention.

According to embodiments of the present invention, methods are alsoprovided wherein an electrochemical cell including a bubble-freeelectrode is used to generate a field in a device, wherein the field isuseful to affect one or more properties of a component of a sample. Forexample, devices are provided according to the present invention whereina bubble-free electrode is employed to generate a field that is used toaffect the mobility of one or more components of a sample, for instance,to cause separation of sample components.

Other embodiments of the present invention include microchip devicesincluding pressure generators configured with frangible or meltableseals and electronics to accomplish precise sample injection andseparation of nanoliter-sized samples.

All patents and publications mentioned herein are incorporated herein intheir entireties by reference.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are only intended to provide a further explanation of the presentinvention, as claimed. The accompanying drawings, which are incorporatedin and constitute a part of this application, illustrate severalexemplary embodiments of the present invention, and, together withdescription, serve to explain the principles of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention may be more fully understood with reference to theaccompanying figures. The figures are intended to illustrate exemplaryembodiments of the present invention without limiting the scope of theinvention.

FIG. 1 is a schematic view of an example of an analytical deviceaccording to an embodiment of the present invention;

FIG. 2 a is a top view of an analytical device according to anembodiment of the present invention;

FIG. 2 b is a cross-sectional view taken along line IIb of FIG. 2 a;

FIG. 3 is a schematic view of an analytical device according to anotherembodiment of the present invention;

FIG. 4 is a schematic view of an analytical device according to yetanother embodiment of the present invention;

FIG. 5 is a top view of a card-type device according to an exemplaryembodiment of the present invention;

FIG. 6 is a side view of a matrix device according to an exemplaryembodiment of the present invention;

FIG. 7 a is a side view of a closed capillary tube analytical deviceaccording to an exemplary embodiment of the present invention;

FIG. 7 b is a top view of a sealing device for sealing the ends of aplurality of capillary tubes, such as the tubes depicted in FIG. 7 a;

FIG. 8 a is a side view of a low frequency concentrator according to anembodiment of the present invention using a pressure driven flow profileto affect separation of components in a sample;

FIG. 8 b is a side view of a component concentrator that uses anelectrophoretic flow profile and component retaining electrodes disposedtransversely with respect to the direction of electrophoretic flow;

FIG. 9 is a top view of an analytical device including a pressuregenerator and frangible seals according to yet another embodiment of thepresent invention;

FIGS. 10-13 are top views of various exemplary analytical devicesaccording to embodiments of the present invention;

FIGS. 14 a and 14 b are a side view and top view, respectively, of ananalytical device according to yet another embodiment of the presentinvention;

FIGS. 15 a, 15 b, and 16 depict various systems used in connection withthe Examples described below;

FIG. 17 is a schematic illustration of an apparatus according to anembodiment of the present invention including an enlarged portionshowing a tip of an epoxy-coated electrode;

FIG. 18 is a schematic drawing illustrating a modified electrode usefulin accordance with embodiments of the present invention;

FIG. 19 is a schematic illustration of an apparatus according to yetanother embodiment of the present invention; and

FIG. 20 is a schematic illustration of an electrophoretic deviceaccording to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

The bubble-free electrodes of the present invention can include avariety of designs and compositions. Different materials and designs canbe used to obtain the bubble-free electrodes of the present invention,including different chemical compounds and combinations of compounds. Anexample of a bubble-free electrode useful in accordance with the presentinvention is a palladium metal anode.

Palladium metal anodes are particularly useful in accordance with anembodiment of the present invention. When palladium is used as a cathodeunder conditions that result in the electrolysis of water, the palladiumis able to store hydrogen generated by the cathode by absorbing thehydrogen in the interstices of the palladium lattice. In metalelectrodes that do not include palladium, hydrogen is not absorbed bythe metal but rather leads to the production of hydrogen gas bubbles atthe electrode surface. According to embodiments of the presentinvention, palladium anodes are provided that include stored hydrogenuseful in preventing the formation of oxygen bubbles at the anode duringoperation of a cell including the anode.

The capacity to store hydrogen is strongly influenced by the temperatureof the anode, the rate at which hydrogen is generated, the morphology ofthe palladium surface, and the crystal grain size of the palladium.Guidance for enabling those skilled in the art to optimize parametersand resulting electrode characteristics is provided by the exemplaryelectrodes, devices, and Examples set forth herein. Once thehydrogen-storing capacity is exceeded, the palladium anode will generatehydrogen bubbles unless something is done to deplete the electrode ofstored hydrogen. The anode can be prepared with hydrogen by reversingthe polarity in this same step to render it a cathode, andsimultaneously the cathode can be run as an anode and depleted ofhydrogen in preparation for the next cycle.

According to embodiments of the present invention wherein anelectrochemical cell is provided and the cell anode is pre-charged underreverse polarity conditions to store hydrogen, the amount of time foroperating the electrode under pre-charging conditions can depend uponthe current and voltage provided by the power supply. A sufficientamount of pre-charging time can be an amount of time under which theanode attains at least about 1% or greater of its hydrogen absorptioncapacity, for example, greater than 50% of its hydrogen absorptioncapacity, greater than 90% of its hydrogen absorption capacity, or toabout the full hydrogen absorption and storage capacity of theelectrode.

Although the palladium metal material and other electrode materials usedaccording to an embodiment of the present invention may not store oxygengas, when a cell including the material is operated under normal anodicoperating conditions following pre-charging, the formation of oxygen gasbubbles at or due to the electrode are prevented or reduced. Instead ofgenerating oxygen gas, the pre-charged palladium or hydrogen-absorbingelectrode, for example anode, of the present invention reacts with thereservoir of hydrogen stored in the pre-charged electrode material. As aresult of pre-charging, the stored hydrogen is oxidized rather thangenerating oxygen gas.

According to an exemplary embodiment of a method and device according tothe present invention, a first electrode, which operates as an anodeunder normal operating conditions, operates as an cathode during areverse-polarity pre-charging preparation process. The first electrodecan be pre-charged ex-situ, or pre-charged in-situ. When pre-chargedin-situ, a device including the electrode can be operated under open orpre-sealed conditions so that bubbles generated by the electrodeoperating as an anode during pre-charging can be vented to theatmosphere while hydrogen accumulates at the hydrogen-absorbingelectrode acting as a cathode during pre-charging. After a pre-chargingperiod of sufficient length to enable the electrode to store an adequateamount of hydrogen under the respective electrical conditions, the cellcan be sealed.

The cell can be pre-charged and then sealed or closed prior to normaloperation or during normal operation. Electrolysis can be discontinuedduring sealing or closing the cell and the cell can subsequently operateunder normal conditions as a bubble-free electrode for a period of time.According to an embodiment of the present invention, the sealed orclosed cell can operate after pre-charging under conditions such that anelectrode, previously pre-charged to store hydrogen, operates as abubble-free anode.

The cell can be pre-charged while simultaneously venting oxygen gasproduced during the pre-charging process. After the preparation andventing, the device can be permanently sealed without the need to ventagain.

According to embodiments of the present invention, a device can becreated that includes an electrochemical cell that can operatebubble-free under normal electrolytic operation for extended periods oftime limited mainly by the volume of hydrogen stored at the electrodeand the ability of the cell to prevent oxygen bubble formation at thecell anode. According to embodiments of the present invention, a devicesuch as that shown in FIG. 9, having, for example, a 10 cm separationchannel, is provided that includes an electrochemical cell that canoperate bubble-free under normal electrolytic operation (i.e., undernormal polarity, not reverse polarity, conditions) for at least about 20minutes at a current of up to about 5 mA and a voltage of up to about 2kV (kilovolts).

According to an embodiment of the present invention, a bubble-free anodeelectrode is provided that does not generate an oxygen bubble at theanode if the current density is held at 72 A/m² (amperes per squaremeter) for one second. This assumes that the solution has beenpreviously degassed and that bubble formation is readily nucleated. Indetermining a condition for bubble-free operation according to anembodiment of the present invention, an electrolysis of pure distilledwater on the surface of an infinite plane electrode was tested atstandard conditions including a temperature of 25° C. and a pressure of1 atm. It was assumed that as a result of the electrolysis, oxygenbubbles would be created on the electrode surface when the oxygenconcentration on that surface reaches a saturation value C_(s). Howquickly this happens depends on the electric current density j at whichthis electrode operates and on initial oxygen concentration C₀ dissolvedin the water. It was also assumed that oxygen is transported away fromthe electrode only by means of diffusion, and the oxygen diffusioncoefficient is D. The time For the oxygen concentration to reach thesaturation value at the surface of the electrode is given by thefollowing formula:t=64×pF²(C _(s) −C _(o))×D/j ²  (1)where F is Faraday's constant and equals=96500 C/mol.Formula (1) allows estimations for critical time as a function ofinitial oxygen concentration and current density. For oxygen C_(s)=1.3mM/L and D=2×10⁻⁵ cm²/s at T=25° C. Assuming that initial oxygenconcentration is 0.1×C_(s), one can calculate that t=5120/j². Thus, t=1second if j=72 A/m². As a reference, the current density in a 50 mmcapillary at a current of 10 mA is about 5000 A/m².

An electrochemical cell is also provided according to the presentinvention that includes a bubble-free palladium anode of suchspecifications. A sample separation device including such an electrodeis also provided by the present invention as is an electrophoreticdevice including such a palladium anode.

According to an embodiment of the present invention, a device foraffecting one or more properties of a component in a sample is providedthat includes a bubble-free electrode. The device can include apalladium electrode as the bubble-free electrode, or some otherelectrode material or combination of materials. An exemplary embodimentis a device including an electrochemical cell having an electrode systemthat includes Mg₂Ni, (RE)Ni₅ wherein RE is a rare earth element, LiNiO₂,V₂O₅, or mixtures, combinations, or combined uses thereof. Otherbubble-free cells and systems that can be used according to embodimentsof the present invention to form a field that affects a property of asample component include reversible electrodes such as those describedin U.S. Pat. No. 5,605,662, galvanic cells, RAM cells, nickel-cadmiumcells, AC voltage-powered electrodes, microfabricated cells and devices,and other bubble-free cells and electrode systems, and combinationsthereof.

According to embodiments of the present invention, an electrochemicalcell is provided that can operate bubble-free under voltage conditionsof at least about 3 volts, for example, at least about 5 volts.According to embodiments of the present invention, an electrochemicalcell is provided that can operate bubble-free under voltage per lengthconditions of at least about 10 volts/cm, for example, at least about 25volts/cm. According to embodiments of the present invention, anelectrochemical cell is provided that can operate bubble-free undervoltage per length conditions of up to about 100 volts/cm. According toembodiments of the present invention, an electrochemical cell isprovided that can operate bubble-free under voltage conditions of up toabout 200 volts/cm. For electrochemical cells according to the presentinvention including hydrogen-absorbing electrodes, the cells can operatebubble-free under these electrical conditions while under electrolyticconditions.

According to an embodiment of the present invention, a device foraffecting one or more properties of a component in a sample is providedthat includes a bubble-free electrode material other than palladium. Anexemplary embodiment is a device including an electrochemical cellhaving an electrode system that includes Mg₂Ni, (RE)Ni₅ wherein RE is arare earth element, LiNiO₂, V₂O₅, or mixtures, combinations, or combineduses thereof.

Other bubble-free electrode materials and systems that can be usedaccording to embodiments of the present invention include RAM cells suchas

-   -   MnO₂, MnOOH|H₂O, KOH|Zn, ZnO,        nickel-cadmium cells such as    -   Cd, CdO|KOH(20% aqueous)|Ni(OH)₄, Ni(OH)₂, Ni,        and others.

According to embodiments of the present invention, electrode materialsfor bubble-free electrode operation in devices and methods of thepresent invention include electroplated iridium oxide electrodes.

According to embodiments of the present invention, electrode materialsfor bubble-free electrode operation in devices and methods of thepresent invention include ionic conductors, polymer electrolytes, liquidelectrolytes, gels, polyethylene oxide (PEO) materials, ceramics such asNASICON, NAFION membranes, and the like, and mixtures and combinationsthereof. The present invention also encompasses combinations of two ormore of these electrode materials as bubble-free electrode materials. Anexample of such a combined material is a mixture of Ni(OH)_(x) electrodematerial with NAFION, PEO materials, gels such as polyacrylamides andgelatin, cross-linked gels, ionic liquid electrolytes such as organicmolten salts, or polymer electrolytes. Electrodes can be made from suchmixed materials or such materials can be used as, for instance, coveringmaterials for electrodes as described in U.S. Pat. Nos. 6,245,508;6,129,828; and 5,849,486, which are herein incorporated in theirentireties by reference. Other electrode or electrolytic materialsuseful according to embodiments of the present invention include ionicliquids, for example, those that behave electronically like salt melts.Exemplary useful liquids according to an embodiment of the presentinvention remain fluid over a temperature range of about 300° C., and/orhave very low vapor pressure. Imidazole-based ionic liquids can be used,including those having the formula:

wherein R is a lower alkyl group of 20 carbon atoms or less, a methylgroup, an ethyl group, a propyl group, a butyl group, or other organicgroups containing about 20 or fewer carbon atoms. The ionic liquid canbe a salt with PF₆ ⁻ as shown, or a salt with another anion.

In addition, other electrode materials and designs that can be used inaccordance with embodiments of the present invention include thoseelectrodes and designs taught in concurrently filed U.S. patentapplication Ser. No. 09/938,894, to Bryning et al., entitled“Manipulation of Analytes Using Electric Fields”, which is incorporatedherein in its entirety by reference.

Finely divided palladium and porous palladium are useful bubble-freeelectrode materials. Methods of manufacturing using these materials canprovide a wide range of advantages. By applying a paste to a substrateand annealing at temperatures of up to 800° C. or higher, or by justdrying the electrodes, the electrodes can be made on various substratesincluding metals, glasses, plastics, and the like, depending on thedesired application.

Bubble-free electrodes according to embodiments of the present inventioncan be chemically stable at a pH of from about 7 to about 9, forexample, at a pH of about 8. Preferably, the electrodes exhibit lowtoxicity and are easily formed.

According to embodiments of the present invention, an analytical deviceis provided that includes an electrochemical cell and a samplecontainment device. The electrochemical cell includes at least an anodicreservoir, a cathodic reservoir, an electrical connection between theanodic reservoir and the cathodic reservoir, and at least a firstbubble-free electrode disposed within one of the anodic reservoir andthe cathodic reservoir. A second electrode is disposed within the otherreservoir and may also be a bubble-free electrode. A power source isprovided having a more positive terminal that is normally in electricalcontact with the first electrode, and a more negative terminal that isnormally in electrical contact with the second electrode. Theelectrochemical cell operates in an electrolytic mode and generates anelectrical field when the power source is turned on and the cell isoperating in a normal mode of operation. The analytical device furtherincludes a power source polarity-inverting device for switching thecontacts between the terminals of the power source and the first andsecond electrodes.

By reversing the polarity of the terminals, the cell can bereverse-charged such that one or more of the electrodes stores orcreates a bubble-preventing compound that prevents formation of bubblesat the electrode surface when the cell is run in the normal electrolyticmode of operation. The sample containment device includes a samplecontainment chamber having an opening for introducing a sample into thechamber. The opening can be positioned with respect to theelectrochemical cell such that an electrical field generated by theelectrochemical cell can influence at least one property, such asmobility, of at least one component of a sample disposed in the samplecontainment chamber.

Because the bubble-free electrodes of the present invention can beembodied in self-contained devices such as card-type devices alreadypreloaded with reagents and separation medium, they are particularlyuseful in integrated disposable devices. More particularly, thebubble-free electrodes of the present invention can be embodied insealed devices such as card-type devices already preloaded with reagentsand separation medium, sealed to prevent evaporation, and containingonly, for example, a sample entrance port, where they are particularlyuseful in integrated disposable devices. The present invention alsoenables low-voltage bubble-free electrodes useful for capturing andmoving biomolecules. Another application of the present invention is inthe form of inexpensive, disposable, washable, or refreshable devicesused in high-throughput laboratories for sample preparation, sampleconcentration, sample purification, sample delivery, and in separationdevices and methods.

Another use according to the present invention is to concentratenegatively charged biomolecules or dye molecules on an electrode andenable plug release into a channel whereby a plug of concentratedbiomolecules can be released into a channel as a single plug or pulse.Another use is to demonstrate concentration and manipulation ofnegatively charged dyes in array-like formats as electrodes on planarsurfaces. Further examples of such devices are described in more detailbelow, such as the devices shown in, and described in connection with,FIGS. 10, 11, 12, 14, and 15.

According to yet another embodiment of the present invention, ananalytical device is provided that includes a flow pathway, a flowmanipulating cell adjacent the flow pathway, and a pressure reliefpathway. The flow manipulating cell includes a confined reservoir, anexit port in communication with the reservoir, and a pressure generatingelectrode in the reservoir. The pressure generating electrode generatesgas bubbles within the reservoir upon application of a controlled powersource for increasing pressure within the cell. The pressure reliefpathway is in communication with the flow pathway and is useful foraffecting a flow through the flow pathway. The pressure-generatingelectrode can be a palladium electrode, for example, a bubble-freepalladium anode of the present invention. The pressure-generatingelectrode can be a palladium anode that runs bubble-free for a timeperiod of at least one second when held at a current density of about 72A/m² in a previously degassed solution. The flow pathway can include anelectrophoretic separation channel. The exit port can include afrangible seal, for example, a heat-meltable seal that is incommunication with a heating element.

The present invention also provides methods of forming bubble-freeelectrodes and electrochemical cells, and analytical devices containingthe same, methods of manipulating components of a sample in an electricfield formed by one or more of the electrodes and/or cells of thepresent invention, and methods of sample injection using apressure-generating electrode according to the present invention. Inaddition, the present invention relates to the use of bubble-freeelectrodes in sample preparation and clean-up applications, in detectionapplications such as described in U.S. Pat. No. 5,833,826, hereinreferred to as “electroflow” applications, in active programmableelectronics devices, in Alien Technology nanoblock circuit technology,in the devices described in U.S. Pat. No. 6,071,394, in self-containedcard devices for diagnostics applications, in sample preparationmethods, in traveling wave separation methods, in multi-step separationmethods, in synchronized cyclic capillary electrophoresis methods, andthe like.

Exemplary devices, systems, and methods which can be adapted accordingto the present invention to employ the bubble-free electrodes andmethods of using same according to the present invention include thosedescribed in U.S. Pat. No. 6,129,828; U.S. Pat. No. 6,099,803; U.S. Pat.No. 6,071,394; U.S. Pat. No. 6,068,818; U.S. Pat. No. 5,965,452; U.S.Pat. No. 5,833,826; U.S. Pat. No. 5,632,957; U.S. Pat. No. 5,605,662;U.S. Pat. No. 5,384,024; U.S. Pat. No. 5,240,576; U.S. Pat. No.4,001,100; International Patent Publication No. WO 00/74850 A2;International Patent Publication No. WO 99/50480; International PatentPublication No. WO 99/14368; and International Patent Publication No. WO98/48084, all of which are incorporated herein in their entireties byreference.

The bubble-free electrodes of the present invention, methods using them,and systems employing them, can be used in a wide variety of devicesthat include one or more electrodes. For example, various embodiments ofthe present invention can be utilized in the capillary electrophoresismicrochips described by Krishnamoorthy et al. in the publicationAnalysis of Sample Injection and Band-Broadening in CapillaryElectrophoresis Microchips, from CFD Research Corporation of HuntsvilleAla.; in the microfluidic analytical devices described by Becker et al.in the publication Polymer microfabrication methods for microfluidicanalytical applications, Electrophoresis, vol. 21, pp. 12-26 (2000); inthe capillary electrophoresis microchips described by Dolnik et al. inthe publication Capillary electrophoresis on microchip, Electrophoresis,vol. 21, pp. 41-54 (2000); in the microfabricated devices described byHuang et al. in the publication Electric Manipulation of Bioparticlesand Macromolecules on Microfabricated Electrodes, Analytical Chemistry,vol. 2001, pp. 1549-1559 (2001); in the micromachining techniques anddevices described by Campaña et al. in the publication Microfabricationof Capillary Electrophoresis Systems Using Micromachining Techniques, J.Micro. Sep. 10, pages 339-355 (1998); in the microfabricated capillaryelectrophoresis channels described by Liu et al. in the publicationOptimization of High-Speed DNA Sequencing on Microfabricated CapillaryElectrophoresis Channels, Analytical Chemistry, vol. 71, pp. 566-573(1999); in the microfluidic systems described by McDonald et al. in thepublication Fabrication of microfluidic systems inpoly(dimethylsiloxane), Electrophoresis, vol. 21, pp. 27-40 (2000); inthe dielectrophoresis submicron bioparticle separation devices andmethods described by Morgan et al. in the publication Separation ofSubmicron Bioparticles by Dielectrophoresis, Biophysical Journal, vol.77, pp. 516-525 (1999); in DNA molecule transportation described byMorishima et al. in the publication Tranportation of DNA MoleculeUtilizing the Conformational Transition in the higher order structure ofDNA, CCAB 97 published on the internet on Feb. 13, 1998; in thetransmission imaging spectrographic and microfabricated channel systemsdescribed by Simpson et al. in the publication A transmission imagingspectrograph and microfabricated channel system for DNA analysis,Electrophoresis, vol. 21, pp 135-149 (2000); in the devices described bySoane et al. in U.S. Pat. No. 5,126,022; in the microchip electrodynamicfocusing device and methods described by Ramsey et al. in U.S. Pat. No.5,858,187; in the electrochemical detectors described by Mathies et al.in U.S. Pat. No. 6,045,676; in the capillary electrophoretic separationsystems described by West et al. in U.S. Pat. No. 6,159,363; in themicrofabricated devices described by Chow et al in U.S. Pat. No.6,174,675 B1; in the microfabricated devices described by Simpson et al.in U.S. Pat. No. 6,236,945 B1; in the microchip devices described byWaters et al. in Microchip Device for Cell Lysis, Multiplex PCRAmplification, and Electrophoretic Sizing, Analytical Chemistry, vol.70, pp. 158-162 (1998); in the biological detection systems described byCheng et al. in PCT International Publication Number WO 00/37163; in themicrofabricated capillary electrophoresis chip described by Mathies etal. in PCT International Publication Number WO 00/42424; in themicrofabrication devices described by Bukshpan in PCT InternationalPublication Number WO 00/73780 A1; in the microlithographic arraysdescribed in PCT International Publication Number WO 94/29707; in thesorting devices described by Austin in PCT International PublicationNumber WO 98/0893; in the electrophoresis chips described by Mathies etal. in PCT International Publication Number WO 98/09161; in thecapillary electrophoretic separation systems described by West et al. inPCT International Publication Number WO 98/49549; in themicrofabrication devices described by Sosnovski et al. in PCTInternational Publication Number WO 99/29711; in the microfabricationdevices described by Ostergaard et al. in PCT International PublicationNumber WO 99/49319; in the microfabricated capillary arrayelectrophoresis chips described by Woolley et al. in Ultra-high speedDNA fragment separations using microfabricated capillary arrayelectrophoresis chips, Proceedings of the National Academy of Sciences,USA vol. 91, pp. 11348-11352 (1994); in the microfabricated devicesdescribed by Woolley et al. in Functional Integration of PCRAmplification and Capillary Electrophoresis in a Microfabricated DNAAnalysis Device, Analytical Chemistry, vol. 68, pp. 4081-4086 (1996);and in the capillary electrophoresis chips described by Woolley et al.in Capillary Electrophoresis Chips with Integrated ElectrochemicalDetection, Analytical Chemistry, vol. 70, pp. 684-688 (1998). All ofthese patents and other publications are incorporated herein in theirentireties by reference.

Referring now to the drawing FIGS., in the embodiment of the presentinvention shown in FIG. 1, palladium electrode 6 and palladium electrode7 are connected to a DC voltage source 1 and placed in closed reservoirs4 and 5, respectively. The electrode 6 operates as an anode and theelectrode 7 operates as a cathode under normal operating conditions. Thenormally-operating anode 6 is pre-charged, for example, prior toinsertion into reservoir 4, or in-situ by reversing the charge on theelectrode for a pre-charging period prior to normal operation.Pre-charging of the anode can be affected by exposure of the electrodeto a hydrogen-rich environment.

Four valves 2 a-2 d are used to fill the reservoirs 4 and 5 withreagent. A capillary tube 3 is inserted into the two reservoirs 4 and 5and filled with reagent. Because of the pre-charging of anode 6, thesystem produces no gas bubbles at anode 6 or at cathode under normaloperating electrolytic conditions. Because no gas bubbles are generatedduring normal operation of the system, the reservoirs and capillary areable to be a closed system. Such a closed system is highly tolerant ofdifferences in elevations of the two reservoirs since siphoning isprevented by the closed system.

An appropriate sample-filling feature such as one of those known tothose skilled in the art, can be incorporated into the system. Dependingupon factors including the charge of the components to be separated froma sample, sample injection can be configured at or near an appropriateend of capillary tube 3.

In an embodiment of the present invention such as shown in FIGS. 2 a and2 b, the system is configured as a microfabricated device 11 including aT-injection feature. The device includes four electrodes 16 a-16 d, atleast one of which includes a bubble-free electrode of the presentinvention. Any suitable leads can be provided for the electrodes 16 a-16d, for example, protruding leads as shown. The device shown in FIGS. 2 aand 2 b can include, for example, four palladium material-containingelectrodes. The electrodes are patterned into wells 12, 13, 14, and 15.A channel 19 is provided between patterned wells 14 and 15, along whichelectrophoretic separation of components of a sample can occur uponappropriate application of charge to electrode pair 16 a and 16 b. Theamount of charge can be any suitable charge, for example, chargesconventionally used, and appropriate charges as taught by the exemplaryembodiments of the present invention described herein. A sampleinjection channel 17 is provided between patterned wells 12 and 13 andcan carry a sample to be separated into electrophoretic separationchannel 19. T-injection of the sample from either of wells 12 or 13 canbe controlled by appropriate charge application to electrode pair 16 cand 16 d.

A sealing cover 18 can be used during operation of the device when thebubble-free electrodes of the present invention are used because nobubbles develop. Because the system can be a closed system duringoperation, no siphoning is required and evaporation can be eliminated orreduced. The device 11 can be loaded and then sealed, as shown, orprovided with one or more access ports through the sealing cover 18.Access ports can be provided, for example, above or otherwise adjacentany number of the patterned wells 12, 13, 14, and 15.

In yet another embodiment of this invention, a system is configured asdepicted in FIG. 3. In this embodiment, a technique known as“electroflow” as described in U.S. Pat. No. 5,833,826, is enabled. Thesystem has four valves 31 a-31 d and palladium electrodes 32 and 33. Anelectric field is established within capillary tube 38 by electrodes 39and 33. Components separated in capillary tube 38 exit the tube at end38′ and are further carried past a detection area in an electric fieldformed between the electrodes 32 and 33. In the embodiment shown,electrode 33 operates as an anode under normal electrolytic operatingconditions.

The palladium electrodes 32 and 33 cause ions exiting the capillary tube38 to flow in a field consistent with the field in the capillary tube38. The present invention allows the electroflow electrodes 32 and 33 tobe positioned very close to the detection cuvette 35. Thus, powersupplies 36 and 37 can operate at lower voltages and still provide afield equal to that in the capillary tube 38 in the area viewed by adetector system. The detector system can include an excitation laser(not shown) and a camera 34 for imaging and color separation. Thisconfiguration also provides a substantial advantage over previousdesigns in that no current has to pass through any of valves 31 a-31 d,and no voltage must pass through reagent contained in the valve orifice.This closed system avoids siphoning from reservoir to reservoir or fromload bar to reservoir.

The load bar 39 can be an array of recesses machined into a conductive,metal bar, electrode, for example, a platinum or stainless steel bar.The ends of separation capillaries can be placed in the recesses alongwith sample, buffer, or both. An appropriate sample injection techniquecan be incorporated into the system or sample reservoir 39′ of load bar39 can be drawn into end 38″ of capillary tube 38.

Another embodiment of this invention is exemplified in FIG. 4. In thisconfiguration, heaters 41, controlled by heater controller 44, raise thetemperature of the palladium electrodes 42 and 46 to increase thehydrogen permeability of the palladium. Two reservoirs 47 a and 47 b arefilled with a suitable conductive buffer through valves 43 a-43 d. Acapillary 45 is filled with the same or a different conductive buffer.Each reservoir 47 a and 47 b has a wet-side communication with itsrespective valves and capillary 45, and a dry side opposite therespective electrodes 46 and 42. Hydrogen not absorbed by negativeelectrode 42 permeates the negative electrode 42 and forms hydrogen gasthat is drawn away by a low pressure source or vacuum 51. A power supply49 is provided. Hydrogen gas is supplied by pump 48 to the positiveelectrode 46 through the dry side of reservoir 47 a where it permeatesthe electrode 46 and is believed to become oxidized such that itprevents the generation of oxygen bubbles. The principal advantage ofthis configuration is that there is no service cycle required topreliminarily charge the positive electrode with atomic hydrogen. Such aconfiguration can run continuously.

An appropriate sample injection feature can be incorporated into thesystem. Depending upon factors including the charges of componentssought to be separated from a sample, sample injection can be configuredat or near an appropriate end of capillary tube 45.

FIG. 5 is a top view of a card type or card style device according to anexemplary embodiment of the present invention. The device can bemicrofabricated to a size as small as one mm long, or shorter.Alternatively, the device can be longer than 1 mm, such as 10 cm orlonger. The device includes a channel system 54, electrode pair 50 and50′, and electrodes 56, 57, 58, and 59. All the electrodes 50, 50′, 56,57, 58, and 59 can be bubble-free electrodes according to one or moreembodiments of the present invention. A sample can be loaded byinjection or other contact with the device at sample access hole 55. Thesample can be pre-loaded, followed by an optional sealing of the device,or provided with an opening for contacting a sample. Sealing the devicecan be accomplished using conventional methods, such as hermeticsealing.

Either or both electrodes of electrode pair 50 and 50′ can be used toconcentrate an analyte flowing in an electrophoretic field betweenelectrodes 56 and 57. AC voltage can be applied to electrode pair 50 and50′ to cause bubble-free flow effects that can advantageously be used toinfluence the flow and separation of sample components. By using thedifferent electrode pairs, different parameters of separation can beachieved, particularly when electrode pair 50 and 50′ are supplied withAC voltage. The result is a tunable system that can be tuned to captureone or more very specific components or biomolecules from a sample. Afurther description of some uses of electrode pair 50 and 50′ will beapparent to those of skill in the art when taken in conjunction with thedescription of FIG. 8 set forth below.

FIG. 5 also illustrates exemplary filters 53 and 53′ and filterlocations. Filters 53 and 53′ can include porous membranes, plasticfilters, gels, semipermeable membranes, anionic membranes, or othersuitable separation devices that preferably can physically separate orisolate one or more components of a sample, and combinations thereof.The positioning of filter 53 allows components to pass through thefilter. Components of a sample can be concentrated on or in filter 53′.

FIG. 6 is a side view of a matrix device according to an exemplaryembodiment of the present invention wherein reference numeral 64 depictsa cover plate or upper plate including access holes (not shown) andwhich is spaced from a substrate 62 which can be made, for example, of aglass or plastic material. Holes provided in substrate 62 are filledwith a plurality of preferably bubble-free electrodes 60 according tothe present invention. The holes in the substrate can be filled with anelectrode paste material, by deposition such as electrodeposition, orplug-type electrodes can be inserted into the holes as by pressing,pouring or melt forming of the electrode material.

The cover plate 64 and the substrate 62 are spaced from each other byway of spacers 65, that can be made, for example, of an elastomericand/or adhesive material. The spacer material can be inert in and toreagents, samples, and conditions used for an analytical techniqueemploying the device. The space between the cover plate 64 and thesubstrate 62 defines a sample containment volume 66 that can be sealedwhen bubble-free electrodes according to the present invention are usedfor the electrodes 60.

Each electrode 60 is provided with a lead or connector 61 for connectionto a power source. Each electrode 60 can be powered by a separate orindependent power source or supply relative to the other electrodes 60,and the voltages to be applied to each electrode may differ to causedifferential attraction and repulsion of analytes. Different voltagescan be applied to the various electrodes at predetermined times forpredetermined time periods for the purpose of moving, separating, and orconcentrating sample components, such as biomolecules from a biologicalsample, to, from, at, or near specific ones of the electrodes. Byreversing the charge applied to one or more specific electrodes, anopposite affinity for specific components can be achieved. For example,by applying an opposite charge, a biomolecule that would be attracted toa specific electrode under positive charge conditions would be repulsedby the electrode under negative charge conditions. As such, desiredmanipulations of biomolecules can be achieved. This embodiment of thepresent invention can particularly advantageously be used in themicrochip matrix devices described in U.S. Pat. No. 6,071,394. Devicesaccording to the present invention can have as many as 100 electrodes ormore in a microfabricated arrangement.

Means such as a control unit can be provided to supply each electrode 60with an independent power or voltage such that each electrode willprovide different affinities to specific sample components than providedby the other electrodes. By changing the voltages applied to the variouselectrodes 60, by providing different voltages to each electrode, and/orby applying voltages to the electrodes for specified or sufficient timeperiods, selective attraction and/or repulsion of specific samplecomponents can be achieved. Furthermore, isolation and concentration ofspecific sample components can be achieved based on known or testedaffinities or repulsions of such components to specific voltages. A morespecific use of such a matrix device is shown in FIGS. 14 a and 14 b ofthe appended drawings, which are described in more detail below.

FIG. 7 a is a side view of closed capillary tube analytical deviceaccording to an exemplary embodiment of the present invention. Thedevice includes two bubble-free electrodes 70 spaced apart at oppositeends of a closed capillary tube 72 and provided with electrode leads orconnectors. The device illustrates a use of the bubble-free electrodesof the present invention in a capillary environment. The device can beused by supplying various voltages or alternating voltages to the twoelectrodes, and can separate, move, concentrate, or otherwise manipulatea sample or components of a sample disposed in the capillary. After asample is loaded into the capillary, as, for instance, by capillaryaction before the electrodes are placed in or on the capillary ends, thedevice can then be sealed by inserting or forming one or both of theelectrodes in the end or ends of the capillary. Because the electrodesare bubble-free electrodes according to the present invention, thedevice can be permanently sealed after the electrodes are placed orformed at the capillary ends. An electrode paste material, electrodeplug, or melt-molded electrode material, for example, can be used.

According to embodiments of the present invention wherein a plurality ofsuch capillary devices can be arranged in an array or structure 700 asshown in FIG. 7 b, a substrate 701 having a plurality of end-sealingelectrodes 703 can be provided with each of the plurality of electrodes703 being centered in a capillary receiving recess 705 formed in thesubstrate 701. The electrodes can be mounted or otherwise fixed orpositioned on the substrate such that by aligning the capillary ends orguiding them with the capillary receiving recesses 701 formed in thesubstrate 701, the plurality of capillaries can be sealed and aplurality of sealed capillary devices according to the present inventioncan be formed simultaneously. For this use, pin-type or pin-shapedelectrodes are suitable and can be sealed, adhered, melted, crimped, orotherwise fixed in place in the capillary ends after insertion ordisposal of samples in the capillaries.

FIG. 8 a is a side view of a concentrator device that can be used, forexample, in the device of FIG. 5 wherein electrodes 73 and 74 of FIG. 8a could be used as electrodes 50 and 50′ of FIG. 5. In FIG. 8 a,opposing electrodes 73 and 74 are disposed on opposite sides of achannel 71. Channel 71 is defined, for example, by a tubular member.According to an embodiment of the present invention, alternating current(AC) can be applied to the opposing electrodes 73 and 74 to create afield between them that affects flow through the channel 71. As shown inFIG. 8 a, trace 800 is the trace of molecules that are relatively slowermoving or slower responding in the electric field formed betweenelectrodes 73 and 74, i.e., 800 is the trace for molecules having a lowcharge to size ratio. Trace 802 is the trace of molecules that arerelatively faster moving or faster responding in the electric fieldformed between electrodes 73 and 74, i.e., 802 is the trace formolecules having a high charge to size ratio. By applying even low ACvoltage between electrodes 73 and 74, manipulation of chargedbiomolecules can be achieved as explained further below.

As shown in FIG. 8 a, the hydrodynamic flow 75 of a flow through channel71 is depicted. The hydrodynamic flow 75 is the profile of the effectivevelocity or the “envelope” of the flow. The hydrodynamic flow 75 hasvarious vector components as illustrated by vectors 76 a-76 c. As shownin FIG. 8 a, the vector or flow in the center of the channel 71,represented as vector 76 c, is faster than the flow at the edges of thechannel 71 represented by vectors 76 a and 76 b, i.e., closer to thewalls of the channel-defining tubular member, hence, the longer vectorlength for vector 76 c. This phenomenon is referred to herein aspressure driven flow.

If a specific biomolecule moves slower in an electric field, it is moreoften moving in the faster moving vector of the fluid flow, i.e., closerto the center of the channel than the sides. If a specific biomoleculemoves faster in an electric field, it is more often moving in the slowermoving vector of the fluid flow, i.e., closer to the sides of thechannel than the center of the channel. As is depicted in FIG. 8 a, thedevice of the present invention is tunable such that the frequency ofspecific biomolecules flowing through channel 71 can be changed oradjusted to selectively concentrate certain components of a sampleflowing through the channel 71. In so doing, positioning of certainbiomolecules or steering certain molecules into relatively faster orslower vectors of the fluid flow can be achieved.

According to an embodiment of the present invention, DC voltage can besupplied to electrodes at opposite ends of the tubular member-definingchannel 71, to cause electrophoretic separation of a sample flowingthrough the channel. In the absence of a gel or sieving medium, allcharged components of the sample should flow through the channel, forexample, in the direction shown by the arrowheads on the traces 800 and802. However, if AC voltage is applied to opposing electrodes such aselectrodes 56 and 57 shown in FIG. 5 to form an electrophoreticseparation channel, some components of the sample moving between thoseelectrodes will move faster between the opposing electrodes 56 and 57,than others. Faster moving components such as faster moving biomoleculescan become attracted to the AC field electrodes (e.g., 50 and 50′ inFIG. 5 or 73 and 74 in FIG. 8 a), and under certain conditions thesefaster moving components can become captured by the AC field electrodes.Furthermore, in devices wherein a sieving medium is provided in anelectrophoretic separation channel, the additional use of ACfield-generating electrodes can provide a comprehensive device havingmultiple dimensions of separation.

Channel sizes for the device of FIG. 8 a can vary depending upon theintended use and size of the device. The channels can vary from about 1micron to about 10 microns in width, for example. The distance betweenthe AC field-generating electrodes 73 and 74 can vary to be any suitabledistance but can be from about 2 microns to many cm. Suitable voltagesto be applied to the AC field-generating electrodes 73 and 74 can befrom about 1000 volts/cm to about 10,000 volts/cm, for example. Thefrequency of the alternating current can be from about 0.1 Hz to about 1kHz, for example, from about 0.1 Hz to about 10 Hz. With highervoltages, lower frequencies can be used. An exemplary voltage supplyscheme entails supplying +/−5 volts to electrodes 73 and 74 at afrequency of about 1 Hz with a separation distance between theelectrodes of about 50 μm (micrometers).

The device of FIG. 8 a, preferably when used in a device such as that ofFIG. 5, can be tunable to achieve specific and effective separation ofcharged biomolecules and can be used to capture only specificbiomolecules of a sample. The device combines the separation attributesof fluid flow or pressure driven flow separation with AC fieldseparation effects.

FIG. 8 b is a side view of a component concentrator that uses anelectrophoretic flow profile and component-retaining electrodes disposedtransversely with respect to the direction of electroosmotic orelectroendoosmotic flow. As shown in FIG. 8 b, the electroendoosmoticflow 805 of a flow through channel 801 is depicted. Theelectroendoosmotic flow 805 is the profile of the effective velocity orthe“envelope” of the flow. The electroendoosmotic flow 805 has variousvector components as illustrated by vectors 806 a-806 c, however, unlikethe differing vectors on the pressure driven flow depicted in FIG. 8 a,the various vectors 806 a-806 c are equivalent under electroendoosmoticflow conditions as depicted in FIG. 8 b. As shown in FIG. 8 b, thevector or flow in the center of the channel 801, represented as vector806 c, is equivalent to the flow at the edges of the channel 801represented by vectors 806 a and 806 b, i.e., closer to the walls of thechannel-defining tubular member.

Electrodes 803 and 804 are placed opposing one another in a directiontransverse to the electroendoosmotic flow through the channel 801. Ifspecific biomolecules 812 are charged and current is applied toelectrodes 803 and 804, the field resulting between opposing electrodes803 and 804 will cause the biomolecules 812 to be drawn-to, held, andconcentrated at least one of the electrodes, electrode 804 in theembodiment shown. Non-charged components 810 will pass through channel801 while a charged component of interest can accumulate on anappropriate electrode, 803 or 804.

As is depicted in FIG. 8 b, the device of the present invention istunable such that the frequency of specific biomolecules flowing throughchannel 801 can be changed or adjusted to selectively concentratecertain components of a sample flowing through the channel 801. In sodoing, accumulating or concentrating certain biomolecules at electrodes803 and 804 in the channel can be achieved.

According to an embodiment of the present invention, DC voltage can besupplied to electrodes at opposite ends of the tubular member-definingchannel 801, to cause electrophoretic separation of a sample flowingthrough the channel. In the absence of a gel or sieving medium, allcharged components of the sample should flow through the channel atequal rates. However, if AC voltage is applied to opposing electrodessuch as electrodes 56 and 57 shown in FIG. 5 to form an electrophoreticseparation channel, some components of the sample moving between thoseelectrodes will move faster between the electrodes than others. Fastermoving components, such as faster moving biomolecules, can becomeattracted to the AC field electrodes (e.g., 50 and 50′ in FIG. 5 or 803and 804 in FIG. 8 b), and under certain conditions these faster movingcomponents can become captured by the AC field electrodes. Furthermore,in devices wherein a sieving medium is provided in an electrophoreticseparation channel, the additional use of AC field-generating electrodescan provide a comprehensive device having multiple dimensions ofseparation.

Channel sizes for the device of FIG. 8 b can vary depending upon theintended use and size of the device. The channels can vary from about 1micron to about 10 microns in width, for example. The distance betweenthe AC field-generating electrodes 803 and 804 can vary to be anysuitable distance but can be from about 2 microns to many cm. Suitablevoltages to be applied to the AC field-generating electrodes 803 and 804can be from about 1000 volts/cm to about 10,000 volts/cm, for example.The frequency of the alternating current can be from about 0.1 Hz toabout 1 kHz, for example, from about 0.1 Hz to about 10 Hz. With highervoltages, lower frequencies can be used. An exemplary voltage supplyscheme entails supplying +/−5 volts to electrodes 803 and 804 at afrequency of about 1 Hz with a separation distance between theelectrodes of about 50 μm (micrometers).

The device of FIG. 8 b, preferably when used in a device such as that ofFIG. 5, can be tunable to achieve specific and effective separation ofcharged biomolecules and can be used to capture only specificbiomolecules of a sample. The device combines the separation attributesof fluid flow or pressure driven flow separation with AC fieldseparation effects.

FIG. 9 is a top view of an analytical device 69 according to yet anotherembodiment of the present invention. The device includes a PCR reactionand sample chamber 77, seals 78, 80, and 824, a reagent container 79, apressure generator 81, a low voltage conduit 82, a channel forelectrophoretic separation 83, buffer containers 84, 86, and 87, lowvoltage conduits 85, 813, 814, 816, 818, 820, and 822, and a highvoltage conduit 85′,

The pressure generator 81 generates pressure, as for example, byincluding at least one gas-generating electrode 850, 852 and conditionsthat enable gas generation. An exemplary system would be agas-generating palladium electrode that has not been pre-chargedaccording to the present invention, and run under conditions as ananode, generating oxygen gas. Other gas-generating electrode systemscould be employed, including platinum electrodes, other gas-generatingmetals, other conducting gas-generating materials, semiconductors, andthe like. The container portion of pressure generator 81 can alsoinclude appropriate buffer or other material needed to causegas-generation, such as an ionic solution. Other generated gases cansimilarly be used to cause sample injection, such as hydrogen gas,chlorine gas, carbon dioxide gas, and the like.

The generation of gas by the pressure generator can be timed with theactivation of current to lead or low voltage conduit 820. Application ofcurrent to conduit 820 is useful for breaking the seal 80 that is madeof a frangible material, for example, a heat-meltable material. The seal80, as well as seals 78 and 824, can include, for example, a paraffinwax material, polyethylene, polypropylene, styrene, plexiglass, or anysuitable meltable plastic material or thermoplastic material. The sealcan be made integral with the material of chip 69 such as formed as partof the channel 830 in the case of seals 78 and 80. Upon melting of seals80 and 78 by application of current to conduits 818 and 820,respectively, pressure generated from pressure generator 81 can flowthrough channel 830, forcing reagent from reagent container 79 to flowfurther down channel 830 past broken or melted seal 78 and cause samplefrom sample container 77 to be forced through channel 834. Uponapplication of current through conduit 816 to melt seal 824, the samplecan be T-injected into channel 83 for electrophoretic separationtherein. Sample flowing from container 77 continues to buffer container86 which can be vented (not shown). Buffer containers 84 and 87, atopposite ends of electrophoretic channel 83, can be vented but may notneed vents if bubble-free electrodes according to embodiments of thepresent invention are employed. Conduit 85′ can be the only high voltageconduit.

Conduits 816, 818, and 820 can be very narrow or made of highlyresistive material and sufficiently charged to locally heat therespective seals and cause them to melt, or to cause opening ofvalve-type re-closable seals. An appropriate power supply for the lowvoltage conduits would be a supply capable of providing from about 1.5to about 30 volts, for example, from about 5 to about 12 volts or fromabout 5 to about 6 volts. The high-voltage supply can supply from about100 to about 10,000 volts, for example, from about 1000 to about 3000volts.

The device shown in FIG. 9 is an exemplary microchip-type device thatcan be used to inject extremely small amount of sample into a separationchannel, and the device can inject extremely small and precise amountsof appropriate reagents and sample as are required when working withnanoliter-sized volumes. The device can be microfabricated and can bemade to be 10 mm long or shorter with appropriate lower voltage use, oras large as 10 cm long or longer. The device can be filled withappropriate reagents and buffers before sealing. Sample can beintroduced before sealing, or the device can be provided with a sampleinjection port at container 77. The channels can be etched or molded orpunched, and the seals can be inserted, deposited or otherwise formed inplace. The substrate for the chip can be made of a glass or plasticmaterial, or the like. The voltage conduits can be laid, welded,electrodeposited, or otherwise deposited.

FIGS. 10-13 are top views of various exemplary analytical devicesaccording to embodiments of the present invention that benefit from thebubble-free electrodes of the present invention. In FIGS. 10-13,Ni(OH)_(x) electrodes 89 are employed adjacent or within channels 88 andaccess ports 90 are provided for the channels. FIG. 10 depicts a simple,high voltage bubble-free chip device. FIG. 11 depicts a device thatemploys the separation technique described with respect to FIG. 8. FIG.12 depicts an exemplary T-injection device for liquid handling whereinsample injection is immediately adjacent an electrode at an end of anelectrophoretic separation channel. FIG. 13 depicts an alternative tothe FIG. 12 embodiment wherein a large sample access port is providedsuch that no filling vent is required in the device. Sample iselectrophoretically transferred through sample injection channel 88′until it reaches and is injected into separation channel 88. In each ofthe devices of FIGS. 10-13, appropriate leads or electrical connectorsare provided for each electrode. In the devices shown in FIGS. 10-12,either access port 90 can be used as a vent for filling sample into theother access port 90.

FIGS. 14 a and 14 b are a side view and top view, respectively, of ananalytical device according to yet another embodiment of the presentinvention similar to the embodiment shown in FIG. 6. In FIGS. 14 a and14 b, array-like devices with Ni(OH)_(x) electrodes are provided. Theelectrodes 95 are formed on or in a substrate 93 and wires 96 areconnected to respective electrodes with silver paste 94. A gasket 92separates a cover glass 91 from the electrodes 95. Access holes 90 areprovided in the cover glass 91. An exemplary length 97 of such a devicecould be about 2 cm.

FIGS. 15 a, 15 b, and 16 depict various systems used to test thebubble-free and gas-generating electrodes of, and used in connectionwith, present invention. In FIG. 15 a, in connection with the Examplesdescribed below.

EXAMPLES

Bulk Porous Electrode Experiment

A device as shown in FIGS. 15 a and 15 b was used in this experiment toallow large volumes of generated oxygen to be released to theatmosphere. The device is a practical device useful for testing thecapacitance of palladium electrodes to last without generating bubbles.The device can compare palladium electrodes to platinum electrodes. FIG.15 a is a side view of the testing device and FIG. 15 b is a bottom viewof the same device. The device includes platinum wires 200, pipette tips202 open at their upper ends, microscopic slides 204 and 205, a porouspalladium electrode 206, a rubber gasket 208, access holes 210 in slide204, and a buffer 212. The cell containing the electrode had dimensionsof 15×15×1 mm. Two access holes were drilled in the upper glass forconnecting the cell to two pipette tips with platinum wires connected inparallel and serving as the opposite electrode. The tested electrode wasmade from nanoporous palladium, grain size 30 nm, specific density 5.424g/cm³ (45% Pd), size 1×1.5×8 mm. At the start, all reservoirs orcontainers were filled with the same buffer material. The Pd electrodewas immersed in the buffer 1.5 mm deep. The volume of Pd exposed to thebuffer was 2.25 mm³. Using Faraday's law, as is known to those skilledin the art, the amount of gas generated by the platinum electrode andabsorbed by the palladium electrode of the present invention can becalculated.

Fresh Electrode Run:

A buffer comprising 10 mM Tris HCl mixed with 1 mM EDTA was used and hada pH of about 8.0. The applied power was a voltage of 100V, an initialcurrent of 3 mA, and a final current of 0.5 mA. No bubbles formed for 50minutes, and the total charge that passed was about 5C (equivalent to0.55 ml of H₂). The polarity was then reversed, and the cell was run atan initial current of 0.5 mA, and a final current of 0.9 mA, whereby noO₂ bubbles formed for 35 minutes.

Repeated Runs:

A buffer was provided and comprised a H₂SO₄ 1:100 dilution. A current of4 mA was applied and the anode ran bubble-free for 5 minutes. With anapplied current of 2.3 mA, the anode ran bubble-free for 10 minutes. Thecharge that passed was ˜1.2C (0.14 ml H₂).

After a few repeated runs, some cracks were observed in the part of theelectrode that is exposed to the buffer because of different expansionof the immersed and non-immersed part of the electrode. The storage ordiffusion of H₂ was negatively affected by the cracks at highercurrents. Some bubbles were observed at sharp edges of the cracks beforethe electrode had reached full capacitance.

Thin Film Electrodes.

Thin Cu wires were soldered to one end of the electrodes. The exposedpart of the wire and the solder were coated with epoxy to preventcontact with buffer. For measurements the electrodes were immersed in abuffer in a small Petri dish. The buffer included 10 mM Tris HCl mixedwith 1 mM EDTA, and had a pH of about 8.0. Applied voltages, currents,and time to formation of H₂ were monitored.

Formation of bubbles was observed under a microscope.

Three types of electrodes were tested:

-   (1) thin film nanoporous Pd 20 μm thick (11×6 mm) baked at 600° C.    on Al₂O₃ substrate;-   (2) thin film nanoporous Pd 40 μm thick (5.5×10 mm) film dried at    100° C., on Al₂O₃ substrate; and-   (3) solid palladium foil 250 μm thick used in U.S. Pat. No.    5,833,826. The foil was coated with epoxy and only one side    dimensioned 14×4 mm was exposed to the buffer.

The conditions for the first electrode were as follows: applied voltage4 V, current 1.1 mA, time to first bubbles 20 min, total charge passed1.3 C. Reversed polarity, current 1.4 mA no O₂ bubbles for 15 minutes.

The conditions for the second electrode were as follows: applied voltage20V, current 10 mA, time to first bubbles 5 min, total charge 3C.

The bubbles in both cases were formed at the edges were the electriccurrent was strongest. For different electrode arrangement, the totalcharge could be higher.

The conditions for the third electrode were as follows. The appliedvoltage was 4V, the applied current was 1 mA, the time until firstbubble formation was 100 min, and the total charge that passed was 6 C.At an applied voltage of 15V, an applied current of 11 mA, for a timeperiod of 30 min, the total charge that passed was 19.8 C. Under reversepolarity conditions, the applied voltage was 10 V, the applied currentwas 6.2 mA, and the time period was for 12 min.

Summary of the Charges Passed for the Tested Pd Electrodes

Charge per mm³ Exposed surface Total Material under exposed area areavolume nanoporous Pd bulk 2.2 C  9 mm² 5.5 mm³ nanoporous film #1   1 C66 mm² 1.3 mm³ nanoporous film #2 1.4 C 55 mm² 2.2 mm³ solid Pd 1.4 C 56mm²  25 mm³Nickel Hydroxide Electrodes

Nickel hydroxides is use in rechargeable alkaline batteries. Unlike Pdelectrodes nickel hydroxides electrodes react with H⁺ and OH⁻ ionswithout generating bubbles of H₂ or O₂ according to the formulae:Ni(OH)₂(s)+2OH⁻⇄Ni(OH)₄(s)+2e⁻ andNi(OH)₄(s)+2H⁺⇄Ni(OH)₂(s)+2H₂O−2e⁻where: (s)—solid, e⁻—electron

The electrode on one side should be connected to an electronic conductor(metal) and parameters like geometry, current densities, grain size,packing density, electronic conductivity of electrodes, crack, etc. playimportant roles in optimizing the system. However, the relatively lowcurrents used in electrophoresis of biomolecules works to an advantage.

Nickel Hydroxide Electrodes Experiment.

Two short glass tubes I.D. 1.5 mm, 10 mm long were packed with mixtureof Ni(OH)₂ and Ni(OH)₄ from partially charged Ni—Cd battery. On oneside, Pt wires were inserted 3 mm inside the mixture and the side wassealed with epoxy. The short tubes then were put on the ends of thinnerglass tubes O.D 1.2 mm, I.D. 0.6 mm, 135 mm long filled with 50 mM Trisbuffer and the gap between them was sealed with epoxy. The two open endsof the longer tubes were placed in a vial filled with 50 nM Tris buffer.

FIG. 16 shows a device for testing the length of time, as determined byvisual inspection, before bubble formation under high voltage conditionsin a nickel hydroxide electrode system. The Pt wires were connected toKEITHLEY electrometer and a high voltage potential of 1000V DC wasapplied, as shown in FIG. 16. In the device of FIG. 16, referencenumeral 215 depicts a KEITHLEY electrometer, 220 and 222 depictelectrodes, and 224 and 226 depict long tubes. The measured currentequaled 275 μA. After 10 min, small bubbles on one electrode werevisible. The total charge passed equaled 0.165 C, which is only afraction of full theoretical capacity of the electrodes (˜10 C). It wasvisible that the packing of the nickel hydroxide was poor and there wasa short path to the Pt wires. To fix the problem a paste of finelypulverized nickel hydroxide is made with NAFION solution as a binder.The specific composition of the paste can be determined by therequirements of the specific application for which it is used.

In conclusion, the two selected materials for bubble-free electrodesworked as expected and together can be used to cover a wide range ofapplications. The palladium electrodes are more expensive but in solidor bulk nanoporous form can be incorporated in reusable devices.Nanoporous palladium ink can be applied by printing on glass orplastics. Solid or baked at higher temperature palladium electrodes havehigh electronic conductivity and are advantageous in high-speedapplications like traveling wave separation. The connection to externalelectronics for the tested electrodes is relatively simple for the samereason.

Nickel hydroxide electrodes are inexpensive, can be easily manufactured,and are useful in disposable devices. The electrodes are optimized foruse as cathodes or anodes.

Electroflow Example 1

Referring now to FIG. 17, an electroflow arrangement is shown forestablishing whether electrodes made of palladium would eliminate thevolume of hydrogen gas that would be generated during a sequencing runon the electroflow breadboard as described in U.S. Pat. No. 5,833,826.As previously mentioned, bubbles generated from electrolysis tend tocomplicate the fluid path and heat management aspects of electroflowbreadboards.

As seen in FIG. 17, the arrangement 100 includes negative electrode 102and positive electrode 104 made of palladium tubing, and having outsidediameters of 1 mm and 0.1 mm walls. The electrodes 102 and 104 wereimmersed in tap water contained in a reservoir 106. The immersion depthof the electrodes was about 3 cm. An electrical system 108 was used tosupply a DC voltage of about 74 V to electrodes 102 and 104 forelectrolysis and the current noted was about 21 mA. The arrangement wasmaintained at a temperature of approximately 21° C. The tip of electrode102 was crimped and provided with an epoxy insulator 103. The role ofthe epoxy insulator was to minimize field concentrations at the edgeprovided by the tip of the electrode 102 and minimize localized bubbleformation.

After a period of approximately 12 minutes, bubbles appeared at thenegative palladium electrode. In order to remove the hydrogen from thenegative electrode 102, the polarity of the electrodes was reversed forapproximately the same amount of time, that is, for approximately 12minutes. It was noted that oxygen gas did not appear at electrode 102,as a positive electrode, for approximately 12 minutes.

The above experiment was repeated three times with approximately thesame results. A vacuum was applied to the negative electrode but noeffect was noted.

The above experiment led to the conclusion that at the notedtemperature, palladium absorbs a certain volume of hydrogen at thesurface only. The current noted in the above experiment, that is, 21 mA,was higher than the usual current for electroflow applications. However,with the assumption that electrolysis times of about 60 minutes orlonger will not be unusual in practice, the electroflow currentcorresponding to available flow cells and plumbing was calculated andverified on an experimental basis as being about 13 mA, as will bedescribed in further detail below. Future modifications can lower thevalue for current to approximately 9 mA, such as a slit height of 0.008inch. It is to be understood that the slit is a rectangular open sectionin the flow cell. By decreasing the height of the slit, the resistivesection of the conductive polymer is decreased, resulting in an increasein the effective resistance through the section. The resistance increaselowers the current for a given voltage as given in Ohm's law.

Considering Equation 1 below:NαT×I  Equation 1where:

-   -   N: the total number of hydrogen atoms absorbed;    -   T: run time of electrolysis in minutes;    -   I: applied current in mA,        what is expressed is that the total number of hydrogen atoms        absorbed is proportional to the run time of electrolysis in        minutes, times the applied current in mA. In Example 1, I was        equal to 21 mA and T was equal to 12 minutes. Therefore:        Nα12 min×21 mA  Equation 2        As previously stated, the electroflow current corresponding to        available flow cells and plumbing was calculated and verified on        an experimental basis as being about 13 mA.        Therefore:        Nα19.4 min×13 mA  Equation 3        In other words, one would have 19.4 minutes of bubble-free run        time in electrolysis with an electrode of the surface area used        in Electroflow Example 1. Increasing the surface area of the        electrode would increase the bubble-free run time. The surface        area of electrode 102 would be: $\begin{matrix}        {\begin{matrix}        {A = {{immersion}\quad{depth} \times 2 \times {radius}\quad{of}\quad{electrode} \times \pi}} \\        {= {{30\quad{mm} \times 2 \times 0.5\quad{mm} \times \pi} = {94.24\quad s\quad{q.\quad{mm}}}}}        \end{matrix}\quad} & {{Equation}\quad 4}        \end{matrix}$        Thus, for an area A of about 94.24 sq.mm, at about 13 mA, the        run time can go up to about 19.4 min without the appearance of        hydrogen gas. Thus, for a run time of about 60 min, the area        must be:        A=(60/19.4)×94.24 sq.mm=292.175 sq.mm  Equation 5

In view of the above, it can be concluded that an electrode having asurface area of approximately 300 sq.mm should work in the arrangementof FIG. 17.

Referring now to FIG. 18, a design for a modified electrode is shown inthe form of electrode 102′. Here, the electrode 102′ includes a sheet ofpalladium measuring about 12.5 mm by 12.5 mm, and having been insulatedat edges thereof with an insulating border 103 bordering an exposedpalladium surface 101.

According to one embodiment of the present invention, a set-up forremoving the hydrogen from the palladium surface can involve a specialhydrogen removal electrode located close to the palladium electrode.This hydrogen removal electrode would be used only during the “cleaning”cycle of the electroflow arrangement. Close proximity would allow veryhigh currents such as 1000 mA to be used at low voltages, such as 12volts DC, over a proportionally short time, such as one minute.

According to an alternative embodiment of the present invention, thepreference of oxygen to react with hydrogen can be exploited. Accordingto this embodiment, two palladium electrodes similar to the onedescribed in FIG. 18 can be used. Prior to using the machine forsequencing, a reverse polarity would be applied to the electrodes. Thiswould saturate the normally positive electrode with hydrogen. During asequencing run, the electrode would be positive, and oxygen would thenreact preferentially with the hydrogen saturated electrode rather thanproduce oxygen bubbles. The negative palladium electrode would absorbthe hydrogen bubbles. At the end of the sequencing cycle, the polarityof the electrodes would again be reversed to “recharge” the electrodesprior to the next sequencing run. It is further possible to use apositive electrode having a surface area of only about one half of thesurface area of the negative electrode since only one atom of oxygen isproduced for every two atoms of hydrogen used. Possible benefits of theabove design include a bubble-free electroflow system, a very shortconductive path for electroflow resulting in substantially lowerelectroflow voltage, no weirs or associated valves, and potential costsavings and enhanced performance.

Electroflow Example 2

Referring now to FIG. 19, a modified version of the arrangement of FIG.17 was used. Here, electrode 102 of FIG. 17 was replaced with electrode102′. Electrode 102′ was a flat sheet of palladium having been placed inthe tap water at an immersion depth of about 11 mm, and further having awidth of about 22 mm. The capacity to absorb hydrogen being a surfacephenomenon, very thin gage or material was used. The edges of electrode102′ were coated with an insulating border 110 made of epoxy in order tominimize field concentrations at the edges of the electrode. Anelectrical system 108 ′ was used to supply a DC voltage of about 50 V toelectrodes 102′ and 104 for electrolysis and the current noted was about13 mA.

After a period of approximately 60 minutes, bubbles appeared at thenegative palladium electrode. In order to remove the hydrogen from thenegative electrode 102′, the polarity of the electrodes was reversed forapproximately the same amount of time, that is, for approximately 60minutes. It was noted that oxygen gas did not appear at electrode 102′,acting as a positive electrode for the duration of the run.

According to one embodiment of the present invention, the principlesdemonstrated in Examples 1 and 2 can be put into practice. In thisregard, reference is now made to FIG. 20, where an electrophoreticarrangement 111 according to an embodiment of the present invention isdepicted in schematic form. Here, a first electrode 112, a secondelectrode 114, and a third electrode 116, all made of palladium, areshown used in conjunction with an array of channels, such as, forexample, capillaries as shown at 124. The second electrode 114 and thirdelectrode 116 are placed in a cuvette 118 supplied with an electrolytesuch as a polymer, for example such as POP6 electrolyte or anothersuitable and/or conventional electrolyte. The electrolyte was suppliedthrough an inlet 122 and the polymer was capable of being dischargedthrough an outlet 120 as shown. The inlet 122 and outlet 120 wereprovided with respective valves 123 and 121 for controlling the flow ofpolymer into and out of the cuvette 118.

In operation, cuvette 118 was first filled with an electrolytic polymer,and valves 121 and 123 were then closed. Then, the third electrode 116was set to be an anode, and the second electrode 114 was set to be acathode. The electrolysis was then run for a period of time to chargethe second electrode 114 to the extent desired. The period of time ofthis first run corresponded approximately to the period of time that thesequencing run was subsequently performed without generating bubbles atthe electrodes. During this first run, oxygen bubbles formed at thesecond electrode 114. Thereafter, the cuvette polymer was washed outwith fresh polymer, and, after a sample injection, the first electrode112 was set to be a cathode, the second electrode 114 was set to be ananode, and the third electrode 116 was set to be a cathode. Anelectrophoresis run was then advantageously made without the formationof bubbles at the second electrode, for the reasons described inrelation to Electroflow Examples 1 and 2 above. In this way, adisruption of the electrophoresis by bubbles was advantageouslyprevented.

The above Electroflow Examples according to the present inventionrepresent uses of the principles of the present invention in anelectrophoretic system similar to the system shown in U.S. Pat. No.5,833,826, the disclosure of which is incorporated herein in itsentirety by reference.

Comparative Examples Using Stainless Steel Electrodes

According to other Experiments, it has been found that, while the use ofstainless steel electrodes leads, after a very short time, to theformation of gas bubbles at those electrodes under conditions ofelectrolysis, the use of electrodes made of palladium, on the otherhand, prevents the formation of such gas bubbles for a much longerperiod of time. It is noted that the period of time during which apalladium electrode absorbs hydrogen atoms during electrolysis is, amongother things, dependent on its exposed surface area, that is, thesurface area available for electrolysis. The larger the exposed surfacearea of the electrode, the longer the period of time during which thepalladium electrode will prevent the formation of gas bubbles underconditions of electrolysis. Stainless steel electrodes, on the otherhand, lead to gas bubble formation in as short a time as 15 seconds.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the embodiments of thepresent invention without departing from the spirit or scope of thepresent invention. Thus, it is intended that the present invention coverother modifications and variations of this invention within the scope ofthe appended claims and their equivalents.

1. An analytical device comprising an electrochemical cell and a samplecontainment device, said electrochemical cell comprising: an anodicreservoir adapted to receive an electrolyte; a cathodic reservoiradapted to receive an electrolyte; a connection between said anodicreservoir and said cathodic reservoir for permitting communication ofelectrolyte from at least one of said reservoirs to the other of saidreservoirs; a first bubble-free electrode having been precharged as acathode to have hydrogen absorbed therein, and the bubble-free electrodebeing disposed within one of said anodic reservoir and said cathodicreservoir; a second electrode disposed within the other of said anodicreservoir and said cathodic reservoir; a power source having a positiveterminal in electrical contact with said first electrode, and a negativeterminal in electrical contact with said second electrode, saidelectrochemical cell operating in an electrolytic mode and generating anelectrical field when said power source is turned on; and a power sourcepolarity inverting device for switching the contacts between theterminals of said power source and said first and second electrodes suchthat said negative terminal is in electrical contact with said firstelectrode and said positive terminal is in electrical contact with saidsecond electrode; and said sample containment device comprising a samplecontainment chamber, said sample containment chamber including anopening for introducing a sample into said chamber and being positionedwith respect to said electrochemical cell such that an electrical fieldgenerated by said electrochemical cell can influence at least oneproperty of at least one component of a sample disposed in said samplecontainment chamber; wherein at least one of said first and secondelectrodes comprises a nickel hydroxide material.
 2. The analyticaldevice of claim 1, wherein said nickel hydroxide material includes anickel hydroxide compound of the formula Ni(OH)_(x) wherein x is 2 or 4.3. An analytical device comprising an electrochemical cell and a samplecontainment device, said electrochemical cell comprising: an anodicreservoir adapted to receive an electrolyte; a cathodic reservoiradapted to receive an electrolyte; a connection between said anodicreservoir and said cathodic reservoir for permitting communication ofelectrolyte from at least one of said reservoirs to the other of saidreservoirs; a first bubble-free electrode having been precharged as acathode to have hydrogen absorbed therein, and the bubble-free electrodebeing disposed within one of said anodic reservoir and said cathodicreservoir; a second electrode disposed within the other of said anodicreservoir and said cathodic reservoir; a power source having a positiveterminal in electrical contact with said first electrode, and a negativeterminal in electrical contact with said second electrode, saidelectrochemical cell operating in an electrolytic mode and generating anelectrical field when said power source is turned on; and a power sourcepolarity inverting device for switching the contacts between theterminals of said power source and said first and second electrodes suchthat said negative terminal is in electrical contact with said firstelectrode and said positive terminal is in electrical contact with saidsecond electrode; and said sample containment device comprising a samplecontainment chamber, said sample containment chamber including anopening for introducing a sample into said chamber and being positionedwith respect to said electrochemical cell such that an electrical fieldgenerated by said electrochemical cell can influence at least oneproperty of at least one component of a sample disposed in said samplecontainment chamber; wherein both of said first and second electrodescomprises a nickel hydroxide material.
 4. The analytical device of claim3, wherein said nickel hydroxide material includes a nickel hydroxidecompound of the formula Ni(OH)_(x) wherein x is 2 or
 4. 5. An analyticaldevice comprising an electrochemical cell and a sample containmentdevice, said electrochemical cell comprising: an anodic reservoiradapted to receive an electrolyte; a cathodic reservoir adapted toreceive an electrolyte; a connection between said anodic reservoir andsaid cathodic reservoir for permitting communication of electrolyte fromat least one of said reservoirs to the other of said reservoirs; a firstbubble-free electrode having been precharged as a cathode to havehydrogen absorbed therein, and the bubble-free electrode being disposedwithin one of said anodic reservoir and said cathodic reservoir; asecond electrode disposed within the other of said anodic reservoir andsaid cathodic reservoir; a power source having a positive terminal inelectrical contact with said first electrode, and a negative terminal inelectrical contact with said second electrode, said electrochemical celloperating in an electrolytic mode and generating an electrical fieldwhen said power source is turned on; and a power source polarityinverting device for switching the contacts between the terminals ofsaid power source and said first and second electrodes such that saidnegative terminal is in electrical contact with said first electrode andsaid positive terminal is in electrical contact with said secondelectrode; and said sample containment device comprising a samplecontainment chamber, said sample containment chamber including anopening for introducing a sample into said chamber and being positionedwith respect to said electrochemical cell such that an electrical fieldgenerated by said electrochemical cell can influence at least oneproperty of at least one component of a sample disposed in said samplecontainment chamber; wherein at least one of said first and secondelectrodes comprises nickel-cadmium.
 6. An analytical device comprisingan electrochemical cell and a sample containment device, saidelectrochemical cell comprising: an anodic reservoir adapted to receivean electrolyte; a cathodic reservoir adapted to receive an electrolyte;a connection between said anodic reservoir and said cathodic reservoirfor permitting communication of electrolyte from at least one of saidreservoirs to the other of said reservoirs; a first bubble-freeelectrode having been precharged as a cathode to have hydrogen absorbedtherein, and the bubble-free electrode being disposed within one of saidanodic reservoir and said cathodic reservoir; a second electrodedisposed within the other of said anodic reservoir and said cathodicreservoir; a power source having a positive terminal in electricalcontact with said first electrode, and a negative terminal in electricalcontact with said second electrode, said electrochemical cell operatingin an electrolytic mode and generating an electrical field when saidpower source is turned on; and a power source polarity inverting devicefor switching the contacts between the terminals of said power sourceand said first and second electrodes such that said negative terminal isin electrical contact with said first electrode and said positiveterminal is in electrical contact with said second electrode; and saidsample containment device comprising a sample containment chamber, saidsample containment chamber including an opening for introducing a sampleinto said chamber and being positioned with respect to saidelectrochemical cell such that an electrical field generated by saidelectrochemical cell can influence at least one property of at least onecomponent of a sample disposed in said sample containment chamber;wherein at least one of said first and second electrodes comprises anionic liquid.
 7. An analytical device comprising an electrochemical celland a sample containment device, said electrochemical cell comprising:an anodic reservoir adapted to receive an electrolyte; a cathodicreservoir adapted to receive an electrolyte; a connection between saidanodic reservoir and said cathodic reservoir for permittingcommunication of electrolyte from at least one of said reservoirs to theother of said reservoirs; a first bubble-free electrode having beenprecharged as a cathode to have hydrogen absorbed therein, and thebubble-free electrode being disposed within one of said anodic reservoirand said cathodic reservoir; a second electrode disposed within theother of said anodic reservoir and said cathodic reservoir; a powersource having a positive terminal in electrical contact with said firstelectrode, and a negative terminal in electrical contact with saidsecond electrode, said electrochemical cell operating in an electrolyticmode and generating an electrical field when said power source is turnedon; and a power source polarity inverting device for switching thecontacts between the terminals of said lower source and said first andsecond electrodes such that said negative terminal is in electricalcontact with said first electrode and said positive terminal is inelectrical contact with said second electrode; and said samplecontainment device comprising a sample containment chamber, said samplecontainment chamber including an opening for introducing a sample intosaid chamber and being positioned with respect to said electrochemicalcell such that an electrical field generated by said electrochemicalcell can influence at least one property of at least one component of asample disposed in said sample containment chamber; wherein at least oneof said first and second electrodes comprises an ionic conductorselected from liquid electrolytes, gels, polymer electrolytes, ceramics,glasses, membranes, and combinations thereof.
 8. An electrochemical cellcomprising: an anodic reservoir adapted to receive an electrolyte; acathodic reservoir adapted to receive an electrolyte; an electricalconnection between said anodic reservoir and said cathodic reservoir forpermitting communication of electrolyte from at least one of saidreservoirs to the other of said reservoirs; a first bubble-free hydrogenabsorbing electrode having been precharged as a cathode to have hydrogenabsorbed therein, and the bubble-free electrode being disposed withinone of said anodic reservoirs and said cathodic reservoir; a secondelectrode disposed within the other of said anodic reservoir and saidcathodic reservoir; a power source having a positive terminal inelectrical contact with said first electrode, and a negative terminal inelectrical contact with said second electrode; and a power sourcepolarity inverting device for switching the contacts between theterminals of said power source and said first and second electrodes suchthat said negative terminal is in electrical contact with said firstelectrode and said positive terminal is in electrical contact with saidsecond electrode; wherein at least one of said first and secondelectrodes comprises a nickel hydroxide material.
 9. The electrochemicalcell of claim 8, wherein said nickel hydroxide material includes anickel hydroxide compound of the formula Ni(OH)_(x) wherein x is either2 or
 4. 10. An electrochemical cell comprising: an anodic reservoiradapted to receive an electrolyte; a cathodic reservoir adapted toreceive an electrolyte; an electrical connection between said anodicreservoir and said cathodic reservoir for permitting communication ofelectrolyte from at least one of said reservoirs to the other of saidreservoirs; a first bubble-free hydrogen absorbing electrode having beenprecharged as a cathode to have hydrogen absorbed therein, and thebubble-free electrode being disposed within one of said anodicreservoirs and said cathodic reservoir; a second electrode disposedwithin the other of said anodic reservoir and said cathodic reservoir; apower source having a positive terminal in electrical contact with saidfirst electrode, and a negative terminal in electrical contact with saidsecond electrode; and a power source polarity inverting device forswitching the contacts between the terminals of said power source andsaid first and second electrodes such that said negative terminal is inelectrical contact with said first electrode and said positive terminalis in electrical contact with said second electrode; wherein both ofsaid first and second electrodes comprises a nickel hydroxide material.11. The electrochemical cell of claim 10, wherein said nickel hydroxidematerial includes a nickel hydroxide compound of the formula Ni(OH)_(x)wherein x is either 2 or
 4. 12. An electrochemical cell comprising; ananodic reservoir adapted to receive an electrolyte; a cathodic reservoiradapted to receive an electrolyte; an electrical connection between saidanodic reservoir and said cathodic reservoir for permittingcommunication of electrolyte from at least one of said reservoirs to theother of said reservoirs; a first bubble-free hydrogen absorbingelectrode having been precharged as a cathode to have hydrogen absorbedtherein, and the bubble-free electrode being disposed within one of saidanodic reservoirs and said cathodic reservoir; a second electrodedisposed within the other of said anodic reservoir and said cathodicreservoir; a power source having a positive terminal in electricalcontact with said first electrode, and a negative terminal in electricalcontact with said second electrode; and a power source polarityinverting device for switching the contacts between the terminals ofsaid power source and said first and second electrodes such that saidnegative terminal is in electrical contact with said first electrode andsaid positive terminal is in electrical contact with said secondelectrode; wherein at least one of said first and second electrodescomprises nickel-cadmium.
 13. An electrochemical cell comprising; ananodic reservoir adapted to receive an electrolyte; a cathodic reservoiradapted to receive an electrolyte; an electrical connection between saidanodic reservoir and said cathodic reservoir for permittingcommunication of electrolyte from at least one of said reservoirs to theother of said reservoirs; a first bubble-free hydrogen absorbingelectrode having been precharged as a cathode to have hydrogen absorbedtherein, and the bubble-free electrode being disposed within one of saidanodic reservoirs and said cathodic reservoir; a second electrodedisposed within the other of said anodic reservoir and said cathodicreservoir; a power source having a positive terminal in electricalcontact with said first electrode, and a negative terminal in electricalcontact with said second electrode; and a power source polarityinverting device for switching the contacts between the terminals ofsaid power source and said first and second electrodes such that saidnegative terminal is in electrical contact with said first electrode andsaid positive terminal is in electrical contact with said secondelectrode; wherein at least one of said first and second electrodescomprises an ionic liquid.
 14. An electrochemical cell comprising; ananodic reservoir adapted to receive an electrolyte; a cathodic reservoiradapted to receive an electrolyte; an electrical connection between saidanodic reservoir and said cathodic reservoir for permittingcommunication of electrolyte from at least one of said reservoirs to theother of said reservoirs; a first bubble-free hydrogen absorbingelectrode having been precharged as a cathode to have hydrogen absorbedtherein, and the bubble-free electrode being disposed within one of saidanodic reservoirs and said cathodic reservoir; a second electrodedisposed within the other of said anodic reservoir and said cathodicreservoir; a power source having a positive terminal in electricalcontact with said first electrode, and a negative terminal in electricalcontact with said second electrode; and a power source polarityinverting device for switching the contacts between the terminals ofsaid power source and said first and second electrodes such that saidnegative terminal is in electrical contact with said first electrode andsaid positive terminal is in electrical contact with said secondelectrode; wherein at least one of said first and second electrodescomprises an ionic conductor selected from liquid electrolytes, gels,polymer electrolytes, ceramics, glasses, membranes, and combinationsthereof.